A coupled arbitrary Lagrangian-Eulerian and Lagrangian method for computation of free surface flows with insoluble surfactants

  • Authors:

  • Sashikumaar Ganesan;Lutz Tobiska

  • Affiliations:

  • Department of Aeronautics, Imperial College of Science, Technology and Medicine, SW7 2AZ London, UK;Institute of Analysis and Numerical Mathematics, Otto-von-Guericke University, PF 4120, D-39016 Magdeburg, Germany

  • Venue:
  • Journal of Computational Physics
  • Year:
  • 2009

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Abstract

A finite element scheme to compute the dynamics of insoluble surfactant on a deforming free surface is presented. The free surface is tracked by the arbitrary Lagrangian-Eulerian (ALE) approach, whereas the surfactant concentration transport equation is approximated in a Lagrangian manner. Since boundary resolved moving meshes are used in the ALE approach, the surface tension, which may be a linear or nonlinear function of surfactant concentration (equation of state), and the Marangoni forces can be incorporated directly into the numerical scheme. Further, the Laplace-Beltrami operator technique, which reduces one order of differentiation associated with the curvature, is used to handle the curvature approximation. A number of 3D-axisymmetric computations are performed to validate the proposed numerical scheme. An excellent surfactant mass conservation without any additional mass correction scheme is obtained. The differences in using a linear and a nonlinear equation of state, respectively, on the flow dynamics of a freely oscillating droplet are demonstrated.